1. Field of Invention
The invention is related to a method for generating and transforming encoding data, and more particularly to a method of generating encoding data and transforming decoding data applied run length limit (RLL) approach.
2. Related Art
The modulation and demodulation mechanism of a record medium, e.g., Compact Disk, or Digital Versatile Disk, is employed to encode original data to digital data via a specific encoding technology since the digital data occupy less storage space of record medium. The digital data are also transformed to the original data through a specific decoding technology. The modulation and demodulation of a record medium usually includes encoding and decoding. The most popular modulation/demodulation technologies of record media are Eight-to-Fourteen Modulations (EFM) applied for Compact Disks and EFMPlus applied for DVD. Both are Run Length Limit approaches of modulation technology.
The coding rate of the modulation and demodulation mechanism directly affects the available data storage space. Furthermore, for simplification of the encoding/decoding procedures and reduction of the original data range, there is a rule of (d, k) limitation that needs to be followed. Therefore, the reference tables for transformation between the original data and the digital data are developed to meet the (d, k) limitation through some auxiliary conditions. Take EFM for example. The EFM provides a coding rate of 8/17 under the (d, k) limitation of (2, 10). However, for linking two arbitrary digital date and meeting the (d, k) limitation, even improving the DC-free control ability, a merging code of three additional digits is added to the digital data of fourteen digits. So the coding efficiency becomes worse and the computing procedure becomes more complicated. EFMPlus provides a coding rate of 8/16 by linking Type and State approach under the (d, k) limitation of (2, 10). However, EFMPlus involves re-using much digital data, i.e., different digital data may be modulated as the same digital data. Therefore, auxiliary conditions are added in the modulation process.